Spreading subtle ads through memes is probably still an under-explored area of marketing and it bypasses modern ad-blocking techniques.

In this vein, I encourage you to search about the 2016 russian interference, and the tactics of the IRA (Internet Research Agency, a russian troll farm). It's been eye-opening for me how was heavily in Twitter/Tumblr in those years about the quantity (and quality) of manipulated memes and astroturfed viral content in social networks.